/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.api.java.summarize.aggregation;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.java.summarize.ObjectColumnSummary;

/**
 * {@link Aggregator} that calculates statistics for {@link Object} values.
 */
@Internal
public class ObjectSummaryAggregator implements Aggregator<Object, ObjectColumnSummary> {

	private long nonNullCount;
	private long nullCount;

	@Override
	public void aggregate(Object value) {
		if (value == null) {
			nullCount++;
		}
		else {
			nonNullCount++;
		}
	}

	@Override
	public void combine(Aggregator<Object, ObjectColumnSummary> otherSameType) {
		ObjectSummaryAggregator other = (ObjectSummaryAggregator) otherSameType;
		nonNullCount += other.nonNullCount;
		nullCount += other.nullCount;
	}

	@Override
	public ObjectColumnSummary result() {
		return new ObjectColumnSummary(nonNullCount, nullCount);
	}
}
